The United States Air Force and its predecessors include a number of specialized Air Force Squadrons. These units vary widely in size and may include several hundred enlisted airmen commanded by an officer in the rank of captain to lieutenant colonel. A squadron may include two or three subordinate flights. In turn the squadron may be part of a group and then a wing. An Air Force squadron is the basic unit of the service and may carry the linage and honors of units over a century ago.